A gas turbine is provided with a compressor that compresses atmospheric air to produce compressed air, combustors that burn fuel in the compressed air to produce a combustion gas, and a turbine that is driven by the combustion gas. The turbine has a turbine rotor rotating about an axis, a plurality of vane stages that are arranged in an axial direction in which the axis extends, and a turbine casing that rotatably covers the turbine rotor. The turbine rotor has a rotor shaft that is centered on the axis and extends in the axial direction, and a plurality of blade stages that are fixed to the rotor shaft. Each of the plurality of blade stages has a plurality of blades arranged around the axis in a circumferential direction. One of the plurality of vane stages is disposed upstream from each of the plurality of blade stages. Each of the plurality of vane stages has a plurality of vanes arranged around the axis in the circumferential direction.
Such a vane is described in, for instance, Patent Literature 1 below. This vane is provided with a vane body that extends in a radial direction with respect to the axis, an outer shroud that is formed at a radially outer side of the vane body, an inner shroud that is formed at a radially inner side of the vane body, and a support rail (or a retainer) that protrudes from the inner shroud to the radially inner side and extends in the circumferential direction.
The support rail is formed with a through-hole passing through it in the axial direction. This through-hole is formed to guide air downstream from an upstream side in the axial direction with respect to the support rail.